Adhesives have been used for a variety of marking, holding, protecting, sealing and masking purposes. Adhesives are used in a wide array of products including tapes, decorative articles, optical and electronic devices, medical uses, structural bonding, and the like. One type of adhesive, a pressure sensitive adhesive, is particularly suitable for many applications.
Pressure sensitive adhesives are well known to one of ordinary skill in the art to possess certain properties at room temperature including the following: (1) aggressive and permanent tack, (2) adherence with no more than finger pressure, (3) sufficient ability to hold onto an adherend, and (4) sufficient cohesive strength to be removed cleanly from the adherend. Materials that have been found to function well as pressure sensitive adhesives are polymers designed and formulated to exhibit the requisite viscoelastic properties resulting in a desired balance of tack, peel adhesion, and shear strength.
The use of adhesives, especially pressure sensitive adhesives, in areas such as the medical, electronic and optical industries is increasing. The requirements of these industries place additional demands upon the adhesive beyond the traditional properties of tack, peel adhesion and shear strength. New classes of materials and new techniques for preparing and delivering pressure sensitive adhesives have been developed to meet the increasingly demanding performance requirements for pressure sensitive adhesives.